ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Oak Ridge National Laboratory 

– Occupational Medical Dose

Document Number:

ORAUT-TKBS-0012-3

Effective Date: 04/20/2004

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 27

Subject Expert: Kenny Fleming

Document Owner

Approval: Signature on File Date: 04/15/2004

Robert Burns, TBD Team Leader

Approval: Signature on File Date: 04/15/2004

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Date: 04/19/2004

Richard E. Toohey, Project Director

Approval: Signature on File Date: 04/20/2004

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

Record of Issue/Revisions ...................................................................................................................

Page

3

Acronyms and Abbreviations ...............................................................................................................4

3.1 Introduction.................................................................................................................................5

3.2 Technical Factors Affecting Diagnostic X-Ray Dose ................................................................... 5

3.2.1 Peak Applied Voltage and Filtration....................................................................................6

3.2.2 Current and Exposure Time ...............................................................................................8

3.2.3 Distance .............................................................................................................................8

3.2.4 Waveform and Collimation Characteristics ......................................................................... 9

3.2.5 Screens, Grids, and Other Factors Potentially Affecting Worker Dose.............................. 10

3.3 Diagnostic X-Ray Doses to ORNL Workers, 1943 to Present.................................................... 10

3.4 Uncertainty Analysis for ORNL Radiography Doses.................................................................. 14

References ........................................................................................................................................25

Glossary ............................................................................................................................................27
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LIST OF TABLES

Table

3-1 Relationship of beam intensity and various technical factors..................................................

Page

10

3-2 X-ray operating parameters, dates of use, and frequency of examinations 

(provided by ORNL) ............................................................................................................... 17

3-3 Assumptions made to operating parameters provided by ORNL and where 

default parameters were used................................................................................................ 18

3-4 Values used to calculate organ dose...................................................................................... 19

3-5 Average absorbed dose per unit entrance air kerma for selected X-ray views, 

organs, and beam qualities .................................................................................................... 20

3-6 Organ dose estimates for ORNL chest and lumbar spine radiographs to be used 

as IREP inputs ....................................................................................................................... 22

3-7 Surrogate and associated organs........................................................................................... 24
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 10/8/2003 00-A Original draft technical basis document addressing 

occupational medical dose for the Oak Ridge National 

Laboratory. Initiated by Kenny Fleming

11/14/2003 11/14/2003 00-B Revised draft in response to formal review comments. 

Initiated by Robert E. Burns, Jr.

04/20/2004 04/20/2004 00 First approved issue. Initiated by Robert E. Burns, Jr.
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 4 of 27

ACRONYMS AND ABBREVIATIONS

Al aluminum

AP anterior-posterior (front-to-back) view

cGy centigray

cm centimeter

DCF dose conversion factor

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

ESE entrance skin exposure

Gy Gray

HVL half value layer

ICRP International Commission on Radiological Protection

ICRU International Commission on Radiological Units and Measurements

IREP Interactive RadioEpidemiological Program

kVp peak applied voltage (in kilovolts)

Lat or Lateral Lateral (or side) view

mA milliampere

mAs milliampere-second

mm millimeter

mrad millirad

NBS National Bureau of Standards (later National Institute of Standards and Technology)

NCRP National Council on Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

ORNL Oak Ridge National Laboratory

ORR Oak Ridge Reservation

PA posterior-anterior (back-to-front) view

PFG photofluorography

R Roentgen

RMS root mean square

SID source-to-image distance

SSD source-to-skin distance

X-10 The Oak Ridge National Laboratory site

Y-12 The Y-12 National Nuclear Security Complex
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 5 of 27

3.1 INTRODUCTION

Diagnostic medical X-ray procedures required as preplacement, annual, and termination examinations 

were and are still a contributor to the occupational radiation exposure of workers at the Oak Ridge 

National Laboratory (ORNL) as defined under the Energy Employees Occupational Illness 

Compensation Program Act of 2000 (EEOICPA). Unlike occupational exposures incurred during 

normal work processes, individual diagnostic medical X-ray exposures were not monitored, 

necessitating the use of the information provided in this document in the reconstruction of acquired 

exposures. This document describes the technical aspects of dose reconstruction from medical Xrays administered prior to employment (preplacement) and periodically thereafter (typically annual 

and termination) as a condition of employment at ORNL. Relatively high-exposure-producing 

photofluorographic (PFG) techniques were used from 1943 through October 3, 1947, to conduct 

preplacement chest examinations for potential ORNL workers. 

Technical Basis Documents and Site Profile Documents are general working documents that provide 

guidance concerning the preparation of dose reconstructions at particular sites or categories of sites. 

They will be revised in the event additional relevant information is obtained about the affected site(s). 

These documents may be used to assist NIOSH in the completion of the individual work required for 

each dose reconstruction. 

In this document the word “facility” is used as a general term for an area, building or group of buildings 

that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy facility” as defined in the Energy Employee 

Occupational Illness Compensation Program Act of 2000 (42 U.S.C. § 7384l (5) and (12)). 

3.2 TECHNICAL FACTORS AFFECTING DIAGNOSTIC X-RAY DOSE

A number of factors affect doses to workers from diagnostic X-ray procedures. For a standard 

medical radiographic (i.e., diagnostic) unit with a tungsten target (anode) and focal spot of 1-2 mm, 

these factors include 

• The peak applied voltage on the X-ray tube (kVp)

• The tube current (mA)

• The time of exposure

• The distance from the X-ray source to the skin or organ of concern

• The waveform of the X-ray generator

• The thickness and type of metal used for filtration (beam hardening)

• The use of collimation or diaphragms to minimize the beam area

• The characteristics of the tube housing

• The type and speed of the film

• Film development procedures

• The use of screens or grids

• The physical size and thickness of the worker

While this list of factors looks formidable, in the absence of direct measurements of the beam itself, 

which might not be available, worker dose can be estimated with a reasonable degree of accuracy 

with knowledge of only the three basic machine parameters (peak applied voltage, tube current, and 

time of exposure) and assumptions about filtration, collimation, and waveform characteristics as 

necessary. The implications of these factors to worker dose are discussed below.
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3.2.1

The energy of the X-ray beam, sometimes referred to as beam quality, is determined by the peak 

applied voltage (kVp) and the filtration. X-rays produced in a typical medical X-ray tube are 

bremsstrahlung radiation (a continuous distribution or spectrum of energies ranging from zero up to 

the voltage applied to the tube). This refers to the electronic potential that exists between the anode 

and cathode of the tube. For a typical unfiltered X-ray spectrum, the average photon energy is about 

one-third of the peak energy, or applied voltage. Hence, most X-rays produced by a given voltage are 

much lower in energy than the applied voltage of the beam, and are attenuated by the filtration that 

exists in the tube (inherent filtration), any additional filtration used to harden the beam, and the torso 

or other portions of the body through which the primary X-ray beam is focused. These X-rays never 

reach the film and are of little value in radiography, but can contribute significantly to worker dose.

Peak Applied Voltage and Filtration

To reduce the worker dose, filtration in the form of a specified thickness of absorbing material 

(typically aluminum) is placed between the beam and the targeted area. This absorbs a large fraction 

of the lower energy X-rays that are of little or no value in making the radiograph while allowing most of 

the more energetic and radiographically useful X-ray photons to pass. In this manner, worker dose is 

reduced significantly and radiographic quality can even be enhanced. A filtered X-ray spectrum has a 

correspondingly higher average energy than it had before it was filtered, although the photon fluence 

rate entering the target area is much reduced. Such a beam is said to have been hardened. A 

corollary to this filtration technique is to use a higher applied voltage and to filter the beam relatively 

heavily to eliminate most of the low-energy, radiographically useless photons from reaching the 

worker.

Beam energy is specified in terms of quality, or hardness, which in turn can be in terms of the half 

value layer (HVL) in aluminum or other metals such as copper or tin. Unfortunately, this parameter is 

seldom available. Even if it is known, it is of limited value, in part because it does not specify the 

maximum energy of the beam. In addition, it might not reflect the true beam quality, as the HVL 

measurement might be biased depending on how it was performed (i.e., if mathematical unfolding 

techniques were not applied to correct for the effect of the absorbers used in the measurement). 

What is commonly, although not always, available is the kVp of the machine and the external filtration 

that might be added for hardening the beam. All X-ray tubes have so-called inherent filtration, which 

includes glass in the walls, oil that surrounds the tube for cooling, and the window or port of the tube 

head. This window, the thinnest part of the tube housing in medical diagnostic units, is typically 

equivalent to 0.5 mm Al in attenuation and, hence, provides little beam hardening. The inherent 

filtration asserted by the ORNL medical department staff for the original X-ray machine installed in 

October 1947 (Picker Model R-2) was 0.04 mm Al. Given the disparity between this value and what is 

typical, a beam quality with an HVL of 1.5 mm Al was assumed for the assessment of worker 

exposures from this unit. The total filtration given for this device was found documented (Lincoln and 

Gupton 1958a and 1958b) as 1 mm Al and was used to estimate the entrance skin exposure1

 1 Throughout this document, italics will be used to differentiate exposure in the special sense from exposure in the 

general sense. Thus exposure refers to exposure in the special sense. Many publications, including NCRP (1985) and 

ICRU (1998), discuss exposure in both the general and special sense. The definition and application of the quantity 

exposure and its concomitant unit the Roentgen have undergone important modifications over the years, as documented in 

the literature.

(ESE) 

values for lumbar spine X-ray examinations for the instrument used between 1947 to 1963. The 

documented skin exposure in these same reports was low (21 mrad) for the PA chest X-ray 

examination as compared to skin exposures from other chest X rays given during that timeframe. The 

skin exposure for that timeframe was estimated using operating parameters.
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Although the benefits of filtration with respect to improved radiographic images were known and 

understood as early as March 1896, within months of the discovery of X-rays (Magie 1896), diagnostic 

radiographs were initially made with no added filtration. Recommendations made in 1937 by the 

International Committee for Radiological Units and Measurements (ICRU), albeit not specific for 

thickness, specified aluminum filters for X-rays of 20 to 120 kVp, which incorporated the diagnostic Xray energy range available at that time (ICRU 1937). Typical external filtration in the 1940s ranged 

from none to 1 mm Al. This was in line with 1936 recommendations of the U.S. Advisory Committee 

on X-Ray and Radium Protection, which later became the National Council on Radiation Protection 

and Measurements (NCRP), which called for 0.5 mm of Al equivalent for radiographic installations, 

and 1 mm Al for fluoroscopy (NBS 1936). In 1949, the NCRP recommended 1-mm Al filtration for 

radiography of thick parts of the body such as the chest (NBS1949); this thickness was used during 

World War II in 100-mA units in larger military hospitals. Recommended thicknesses were later 

increased; in 1955, the NCRP recommendation for diagnostic X-ray units called for 2-mm total Al 

filtration for new machines (NBS 1955). This increased in 1968 to 2.5 mm for medical diagnostic units 

operating above 70 kVp (NCRP 1968). For machines already in operation, these recommended filter 

thicknesses might not have been used for some time after the date of the recommendation.

The relationship of beam intensity2

I = Ioe-0.4t

to applied voltage and filtration is complex and to some extent 

machine-specific and, therefore, is best determined empirically. In the absence of empirical data for a 

specific machine, however, there are adequate contemporary empirical and theoretical data on which 

to determine machine output within a reasonable degree of uncertainty. Additional filtration reduces 

the ESE, generally in an exponential manner. For a typical single-phase, half-, full-, or self-rectified 

machine operating in the diagnostic range of 80 to 100 kVp, each additional millimeter of Al filtration 

will effect a reduction of about 40% in the ESE (Trout, Kelley, and Cathey 1952; Taylor 1957). Thus, 

the approximate intensity reduction afforded by any thickness of Al filtration can be determined by the 

following exponential equation:

or

ln (I/Io) = -0.4 t

where t is the thickness of Al in millimeters, and I and Io are the beam intensities with and without the 

filter, respectively. In the absence of specific measurements or empirical data, this correction, which 

is consistent with the guidance in External Dose Reconstruction Implementation Guideline (NIOSH 

2002), can be applied to determine the effect of filtration on beam intensity.

Similarly, increasing the kVp will increase the beam intensity or exposure rate. This can be calculated 

using Kramer’s rule, but such calculations are difficult, complex, and time-consuming, even with highspeed computers, and are at best approximations. However, many empirical studies of beam 

intensity as a function of kVp provide ample credible evidence to show that, for a given amount of 

filtration, increasing the applied kVp will increase the beam intensity according to the 1.7 power of the 

applied kilovoltage (Handloser 1951; Trout, Kelley, and Cathey 1952; Kathren 1965; BRH 1970). In 

the absence of specific measurements or empirical data, this function, which is consistent with the 

guidance in NIOSH (2002), can be applied to determine the effect of applied voltage on beam 

intensity.

 2 As used herein, beam intensity refers to the output of the machine in terms of exposure in the special sense per 

mAs. Exposure in the special sense is referenced to ionization in air and, as such, is not a dose quantity. 
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3.2.2

Diagnostic X-ray exposures are typically specified in terms of milliampere-seconds (mAs), the product 

of X-ray tube current and exposure time. Thus, all factors being equal (e.g., kVp, filtration, film speed, 

development, and screen combination), radiation exposure is directly proportional to the product of 

the tube current and exposure time, mAs. The current in an X-ray tube refers to the number of 

electrons accelerated across the evacuated volume of the tube, flowing from the cathode to the 

anode. For a given applied voltage, the number of X-ray photons produced, and therefore the 

exposure, will, at least in theory, be directly proportional to the X-ray tube current. This is and has 

been true for most medical radiography units over their design tube current range. Thus, in the 

absence of measurements or other data or information to the contrary, it is reasonable and consistent 

with long-standing radiographic practice (Sante 1946) to assume linearity of exposure with tube 

current for a given kVp and filtration.

Current and Exposure Time

Exposure time refers to the period the beam was on or the machine was producing X-rays and is, for 

all practical purposes, linear with exposure. To avoid or minimize image blurring from the beating 

heart, exposure time for chest radiography was minimized, and the current proportionally increased to 

obtain the desired exposure in terms of mAs. However, from a dose reconstruction standpoint, earlier 

medical radiographic units had mechanical timers with accuracies that were not as good as those of 

the electronic timers used on later units. It was noted in two surveys conducted at ORNL (Ohnesorge 

1979 and Halliburton 1985) that the timer for the Westinghouse Riviera instrument was incorrect by 

between 20 to 25%. Because of these two consistent measurements, the ESE for the Westinghouse 

unit (1963 - 1990) given in Table 3-4 (and thus the corresponding organ doses in Table 3-6) were 

increased by 25%. Gross systematic errors in timer accuracy, however, are typically unlikely in most 

units because they would result in over- or underexposure of the radiograph and, therefore, would be 

quickly detected and corrected. Small random errors, which might produce uncertainties of perhaps 

±20% in the exposure, are more subtle. 

Photofluorography of the chest, which resulted in much greater worker doses than a standard 

radiographic procedure, appears to have been used by Oak Ridge Hospital from the inception of 

activities at ORNL (ca. early 1943) until the ORNL Medical Department began using its own 

conventional diagnostic X-ray machine in early October 1947. It was stated by the Radiology 

Technician that began working at ORNL in September 1947 that no PFG exams of the chest were 

performed at the ORNL site during physical examinations and none were observed during the site 

visit. Although PFG examinations were used as an inexpensive method of conducting tuberculosis 

screenings for large populations, they caused much higher exposures than conventional radiographic 

chest X-ray examinations due to the need for increased exposure time to fluoresce the image screen. 

It appears that stereoscopic PFG views (with 2 exposures) using smaller film (4 × 10 in.) were used to 

conduct preplacement examinations for all ORNL workers from 1943 through September 1947. It 

also appears that if the initial examination indicated the need for a follow-up, these were performed 

via a conventional posterior-anterior (PA) view onto 14- × 17-in. film. (A fluoroscopy X-ray unit was 

acquired at some time early in the history of the ORNL site, but was used for a short period of time 

and only for conducting upper gastro-intestinal examinations.)

3.2.3

X-ray beam intensity is a function of distance from the target, approximating the inverse square at 

large distances from the tube. Radiographic chest films were taken at a standard source-to-image 

distance (SID)

Distance

3

 3 Also known as film-to-focus distance (FFD).

of 72 in. (source refers to the focal spot of the tube and image to the plane of the film). 
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The distance to the worker, who was between the source and the film cassette, sometimes expressed 

in terms of the source-to-skin distance (SSD), was somewhat smaller and, therefore, the ESE to the 

worker was somewhat greater than the exposure at the plane of the film. In addition, patient size can 

further reduce or attenuate the number of photons that can pass through the worker and reach the 

film. To compensate for the increased attenuation and scattering of X-rays provided by a larger 

worker, X-ray technicians would sometimes increase the beam settings or, if the machine was so 

equipped, might use a high-speed Potter-Bucky diaphragm, probably with a somewhat higher applied 

voltage. Therefore it might be appropriate for an individual dose reconstruction to increase the ESE 

for a large or stout worker if this information is known. Based on standard contemporary techniques 

(Picker 1941; Fuchs 1958; Cahoon 1961) for workers with a chest thickness of 25 to 27 cm, an 

increase of +50% from the ESE to the average worker should be sufficiently conservative; for still 

larger workers, a factor of 2 would be appropriate. [PA Chest and Anterior Posterior (AP) Lumbar 

spine thicknesses were assumed to be 26 cm while the thickness of the Lateral Chest and Lateral 

Lumbar Spine was 34 cm. It further was assumed that a distance of 5 cm existed between the film 

and the closest surface of the body to the film. These measurements are reasonable and were used 

to estimate the ESEs for the various X-ray examinations for ORNL employees.)

3.2.4

Among other factors that could affect worker dose are waveform and collimation. X-ray waveforms 

are of three types: half-wave rectified, which were present in the earliest X-ray equipment; full-wave 

rectified; and constant potential. A half-wave rectified machine produces 60 half-sinusoidal shaped 

pulses of X-rays per second, each with a duration of 1/120 of a second. A full-wave rectified machine 

produces 120 half-sinusoidal pulses per second, each with a duration of 1/120 second. Thus, for a 

given setting of kVp and mA, the intensity of the beam from a half-wave rectified machine is half that 

of the beam from the full-wave rectified type. A constant potential machine produces a more or less 

steady (i.e., unpulsed) output of X-rays and has a somewhat greater beam intensity – approximately 

10% more – than a full-wave rectified machine operating at the same kVp and mA. (It was assumed 

that single phase units were used until 1990 when a constant potential unit was procured for ORNL.)

Waveform and Collimation Characteristics

Collimation refers to the size of beam and how it is focused on the target area. The early philosophy 

was to use a fairly large aperture with limited collimation to ensure that the entire area of interest was 

included in the radiograph. Later, because of radiation exposure concerns, beams were collimated 

such that the smallest beam consistent with the area of interest was used, thereby limiting the area of 

the patient exposed and, in the case of chest radiography, minimizing dose to organs such as gonads, 

thyroid, and gastrointestinal tract. A practical check of collimation can be made by reference to the 

radiograph; a well-collimated beam will leave a small unexposed area or penumbra effect at the 

edges of the radiograph, while a poorly collimated beam will produce a radiograph that is exposed 

over all of its area. Discussions with the radiology technician who worked at ORNL from 1947 until 

recently indicated that the X-ray beams used at ORNL were well collimated (Tuck 2003) and a paper 

(Lincoln and Gupton 1958a) indicates that a 20 cm cone was used in the mid 1950s at ORNL to 

reduce secondary photons and therefore to collimated the primary beam. Results given in a table 

(Lincoln and Gupton 1958a) indicate that the dose conversion factors (DCFs) given in ICRP 34 for a 

well collimated beam may not apply and therefore uncollimated DCFs found in ORAUT-OTIB-0006, 

Table 4.0-1 (ORAU 2003), were used until a newer X-ray unit was procured in 1963. Another 

document from the same author (Lincoln and Gupton 1958b) stated that “Gonad doses determined 

from these phantom measurements are probably exaggerated, as the phantom is somewhat smaller 

than the average adult.”
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3.2.5

A number of other factors affect the X-ray exposure required to obtain a proper radiograph and, 

therefore, the dose to the worker. Knowledge of these factors is unnecessary for dose reconstruction 

purposes if beam measurements are available or if the primary machine characteristics of applied 

voltage, time, and current are known along with the amount of primary beam filtration. However, the 

factors can be used as additional confirmation of the applicability of the reconstructed dose. For 

completeness, this document mentions these factors, which are tube housing, type and speed of film, 

development procedure, screens, and grids.

Screens, Grids, and Other Factors Potentially Affecting Worker Dose

X-ray tubes used for diagnostic radiography are typically enclosed in protective lead tube housings 

and the primary beam is emitted through a port or window in the side of the housing. Although some 

reduction of worker dose is achieved, largely through elimination of scattered radiation and improved 

collimation, the primary purpose of the diagnostic tube housing is the protection of the operator, 

unexposed X-ray film, and nearby individuals other than the worker. This issue is moot, however, 

because virtually all X-ray tubes, and certainly those used at ORNL since its inception, had protective 

tube housings.

The amount of exposure needed for a suitable diagnostic radiograph is in some measure a function of 

film speed and development. Fine grain emulsions produce a superior radiographic image but require 

additional exposure in comparison to fast films. In addition, underdevelopment of films requires 

additional exposure to achieve satisfactory radiographic quality. Intensifying screens are used in the 

cassette to augment the radiographic effect and thereby increase film speed and reduce worker dose. 

Grids, specifically the Potter-Bucky diaphragm (colloquially known as a Bucky), are sometimes utilized 

for thick section radiography, but rarely for chest radiography except with large workers. In any case, 

the above (i.e., kVp, mA, exposure time, and filtration) are all factored into the technique used and, 

except in rare instances and a virtually complete absence of other data, are not important in dose 

reconstruction.

3.3 DIAGNOSTIC X-RAY DOSES TO ORNL WORKERS, 1943 TO PRESENT 

For convenience and possible application to cases in which the standard ORNL protocol was not 

followed, or for generic use, the effects of various technical factors and how they affect X-ray beam 

intensity are summarized in Table 3-1.

Table 3-1. Relationship of beam intensity and various technical factors.

Parameter Units Relationship with intensity

Applied voltage kVp Intensity proportional to 1.7 power of kVp

Tube current mA Linear

Exposure time s Linear

Filtration mm Al Intensity decreases by ~40% for each additional mm Al

Worker size

(chest thickness) 

25-27 mm

> 27 mm

Dose increased by factor of 1.5

Dose increased by factor of 2

Distance d Approximately inverse square relations (1/d2)

Uncertainty ±30 % Assume all errors are positive, +30% should be used

The current ORNL Medical Department provided a description of radiographic techniques that have 

been used to conduct X-ray examinations for workers at the ORNL site (ORNL 2002, see Table 3-2). 

Before October 3, 1947, all radiology examinations were performed at Oak Ridge Hospital in Oak 

Ridge, Tennessee. A review of several individual records in the ORNL Medical Records vault seems 

to confirm that many early preplacement medical examinations were conducted at Oak Ridge Hospital 

from 1943 through 1947. The vault contains 4- × 10-in., stereoscopic PFG images; a sampling of 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 11 of 27

~15% of these images indicated beginning and end dates of March 1944 and September 1945, 

respectively, for the examinations. The ESE and organ dose values in Tables 3-4 and 3-6, 

respectively, for PFG examinations are based on the assumption that stereo imaging was always 

employed for such examinations; that is, each procedure consisted of two exposures for each 

individual. If it is determined that a PFG conducted for a given individual consisted of only one 4- × 5-

in. view, the values in these tables should be divided by 2. Although 14- × 17-in. radiographic PA 

images were in individual medical X-ray files from 1943 through 1947, the use of stereo PFG for 

preplacement examinations during that period cannot be discounted. Such examinations should be 

assumed, therefore, for each individual who began employment during that period unless there is 

evidence to the contrary. Almost exclusively, individual medical files noted that retake, routine annual, 

and termination X-ray films taken from 1943 through 1947 were 14- × 17-in. radiographic PA images. 

[However, during the review of radiographic images archived by the ORNL medical department, two 

stereo PFG films were located for an individual that were taken approximately 1 year apart. The initial 

PFG was followed approximately 2 weeks later with a 14- × 17-in. radiographic PA image due to 

problems in viewing the initial film. The medical record indicated that an annual chest X-ray was 

taken approximately 1 year after the initial PFG. This annual chest X-ray was a PFG examination.]

The use of PFG imaging was common during that period because it was less expensive than the 

conventional (e.g., larger) X-ray films and could quickly be used as a means of screening large 

numbers of individuals for tuberculosis, which was a public health concern at the time. As needed, 

follow-up examinations with conventional-sized films (e.g., 14- × 17-in.) were taken to either confirm 

original results or to get clearer images. 

There is an indication from documentation at Y-12 that some medical examinations were performed in 

Knoxville, Tennessee, but it is not known at what frequency these were performed or if medical X-rays 

for employment purposes for ORNL workers were ever taken in Knoxville. All diagnostic X-ray films 

reviewed in the ORNL Medical Records vault were inscribed either “OR Hospital” or “Oak Ridge 

National Lab.” Nonetheless, the assumption of a 0.2-R exposure for a PA chest radiograph at a 

Knoxville hospital would be claimant-favorable, and the absorbed dose values in Table 3-6 can be 

used to estimate organ doses for other hospitals in the 1940s that might have performed PA chest Xray examinations. [The United States Army Center for Health Protection and Preventative Medicine 

(USACHPPM) was contacted, but no historic information regarding type of equipment used, 

procedures, or equipment operating parameters was obtained nor was information that Oak Ridge 

Hospital even existed as an Army hospital.] Oak Ridge Hospital became Methodist Hospital of Oak 

Ridge in 1959. Historical records transferred from Oak Ridge Hospital to ORNL appear to have either 

been incorporated in individual medical files or remain in the X-ray pouches. Based on the gaps in 

time for the PFGs noted above, it is not clear if all medical and X-ray records were transferred from 

Oak Ridge Hospital to ORNL Medical. It is possible that records were sent to the Oak Ridge 

Reservation (ORR) site at which the employee was active at the time and were not transferred with 

them when they transferred to other ORR sites.

Information provided by the ORNL medical department indicated that from October 3, 1947, to the 

present, all medical X-rays for employment conducted in the ORNL Medical area used conventional, 

diagnostic radiographic (non-PFG) equipment. A fluoroscopic unit was used at ORNL at one point for 

conducting upper gastrointestinal (GI) series examinations, but was never used for examinations that 

would be considered occupational exposure under EEOICPA. 

After ORNL stopped performing upper GI examinations (believed to be in the early 1950s), and at K. 

Z. Morgan’s request, the Radiology Technician (RT) constructed a shield from the rubberized-lead, 

fluoroscopy apron that male workers could use to shield their gonads during routine employment 

screenings (Tuck 2003). (The RT added that K. Z. Morgan was adamant about radiation protection in
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 12 of 27

medical procedures.) The RT stated that workers would hold the shield at approximately waist level 

for a PA chest exam or place it across their thighs for AP (or similar) shots. It was the RT’s assertion 

that only male workers would use the shield, as it would interfere with the region of interest if females 

used it to shield the ovaries. The RT would check the shield for leaks by exposing an X-ray cassette 

with the shield in front of it. Use of the shield was discontinued (the RT could not recall when) in favor 

of collimation of the X-ray beam. 

Table 3-2 lists radiographic examinations that would be considered occupational medical exposures 

for workers at ORNL after October 3, 1947, identifying the equipment and operating parameters used 

during the different periods. Two items in the description provided by the ORNL Medical Department 

that appear to be inconsistent for equipment in use at the time are the inherent (and total) filtration of 

the initial Picker unit and the exposure time used with the Westinghouse Riviera unit. Typical inherent 

filtration for an X-ray tube at the time was approximately 0.5 mm Al (TM 1944), with additional filtration 

between the beam source and target to harden it. The exposure time of 0.01 sec with a tube current 

of 300 mA gives a 3-mAs intensity, which was believed to be low for that period. Rather than using 

the given 0.01-sec exposure time, it is assumed that the exposure time was 0.1 sec, making 

exposures for PA chest films 30 mAs when using the Picker X-ray unit. The radiology examinations 

performed at ORNL are listed below:

• Chest: PA and lateral

• Lumbar spine series: AP, AP Spot, lateral, and lateral spot

Accordingly, only doses from these techniques, in addition to the PFG exams conducted at the Oak 

Ridge Hospital from 1943 to 1947, were evaluated to support dose reconstructions at the ORNL site. 

Table 3-2 lists the three radiographic instruments that have been used at ORNL and the applied 

voltage, tube current, exposure time, and SID used for examinations. Medical records for individuals 

who worked at ORNL in the early years indicated that preplacement, routine annual, and termination 

radiographic chest examinations were the norm until the 1970s, when individuals were able to waive 

annual chest X-ray examinations. [Information in the individual’s medical files and X-ray log books 

available in the ORNL Medical Records vault should enable a dose reconstructor to accurately 

estimate an individual’s occupational medical X-ray examination record from October 3, 1947. 

Information for workers who worked at the site from 1943 to October 3, 1947, was present in many of 

the medical files that were reviewed and this information may be provided by the ORNL Medical staff 

for use by the dose reconstructor to determine number of examinations.]

The lumbar spine series of examinations was reserved for preplacement X-ray examinations for craft 

employees (pipefitters, carpenters, etc.) to determine if they had pre-existing back problems prior to 

hiring. The information provided by the ORNL medical department indicated that the Lumbar Spine 

series of examinations, which took place from April 6, 1950, to September 23, 1953, would have been 

conducted along with a PA chest examination. Although the spot X-ray examinations would have 

used conic or cylindrical shields to reduce the size of the field and, therefore, would have significantly 

reduced exposures to organs outside the field of view, the ESEs within the field would have been 

unlikely to change. For dose reconstruction purposes, it is assumed that two AP and two lateral 

lumbar spine examinations would have been conducted on preplacement individuals during this 

period and this is claimant favorable.

Field surveys provided by the ORNL RT at the Oak Ridge Hospital indicated that the skin exposure for 

a single exposure PA Chest PFG was 1.4 R (or 2.8 R for the 2 PA Chest PFG exposures). This value 

should be used for individuals whose medical records indicate a preplacement chest X-ray 

examination prior to October 3, 1947, unless the records indicate that a PFG exam was not used. In 

addition, the ESE and organ dose values provided for PFG exams should be divided by 2 if it is 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 13 of 27

known that only a single PFG exposure was made. Any confirmed retake, annual, or termination 

chest X-ray exams should assume that standard 14- × 17-in. PA films were made unless otherwise 

noted in the medical records. Organ doses have been provided for each of these cases. 

A potential problem common to all X-ray examination procedures relates to the conversion of 

exposure represented by ESE to absorbed organ dose, and to changes in the definition of dose and 

other dose quantities. Over the 50 or so years since the beginning of ORNL operations, the quantity 

known today as exposure has undergone several important conceptual changes, as has the 

application of the unit of exposure, the Roentgen (R), which in itself is obsolete. Thus, there is much 

confusion about the definition of exposure and its associated unit. At one time, the Roentgen was 

used to quantify the dose from electromagnetic radiation in air and, when this proved confusing and 

inexact, was defined as exposure dose to distinguish it from the term absorbed dose, which was 

applicable to any type of radiation.

Additional confusion was engendered by changes in the values of the conversion coefficients used to 

convert exposure to absorbed dose. At various times an exposure of 1 R was equated to a soft tissue 

dose of 0.83, 0.877, or 0.93 rad. Thus, an exposure to air of 1 R would result in an absorbed dose of 

somewhat less than 1 rad (1 cGy = 10 mGy). Nonetheless, regulations applicable to ORNL and other 

DOE sites defined 1 R as exactly equal to a dose of 1 rad (10 mGy), thereby producing an 

overestimate in the reported dose or dose equivalent because dosimeters were typically calibrated 

against a field measured in R, which was numerically equated as absorbed dose in rad (Kathren and 

Petersen 1989). Further complicating the conversion of ESE in terms of exposure to absorbed dose 

is the contemporary trend to refer to X-ray intensity in terms of the quantity kerma, which is measured 

in the same units as absorbed dose. Typically, the numerical value of kerma is slightly lower than the 

corresponding value of absorbed dose. Thus, to ensure conservatism and compliance with National 

Institute for Occupational Safety and Health (NIOSH) guidance document OCAS-IG-001 (NIOSH 

2002), and to avoid any risk of dose underestimation, 1 R of exposure was taken to be equal to1 rad 

of absorbed dose and to 1 rad (10 mGy) of kerma. 

The ESE values for each X-ray generating device and examination technique used at ORNL are listed 

in Table 3-4. If measured ESE data were not obtained from literature, ESEs were estimated based on 

knowledge of the operating parameters of the X-ray tube, assumed worker thickness, assumed 

distance between worker and film, and technique used. Both Lincoln and Gupton documents (1958a 

and 1958b) provided measured ESE values for lumbar spine examinations conducted in the mid 

1950s. These values were used to estimate organ doses given in Table 3-6. In addition, measured 

exposures to the testes, ovaries, and skin were used from this document when available.

[Identification and operating parameters for X-ray equipment at Oak Ridge Hospital in use from 1943 

through October 3, 1947 were not located. However, a survey of the Hospital’s PFG unit indicated an 

exposure to the skin of 1.4 R. The ESE values for examinations at Oak Ridge Hospital of 2.8 R and 

0.2 R are to be used for stereo PFG (two exposures) and PA chest procedures, respectively.] The 

skin exposure value of 1.4 R was obtained from the survey conducted in 1956 of the PFG unit at the 

Oak Ridge Hospital and assumed to be the claimant favorable value used for the ESE. This value 

was doubled to 2.8 to account for two PFG exposures. An ESE value of 0.2 R should be used for 

each radiographic PA chest examination noted for an individual prior to examinations conducted at 

ORNL in October 1947, and for any PA chest examination after this time that is known to have 

occurred outside the ORNL Medical department (unless a better-known ESE value is available for the 

outside examination). 

Conversions from ESEs to organ doses were done using DCFs from Tables A2 through A9 of ICRP 

Publication 34, “Protection of the Patient in Diagnostic Radiology” (ICRP 1982), where the photon 

beams were well collimated. However, early X-ray units typically did not provide adequate collimation 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 14 of 27

to reduce organ exposures outside the primary beam. Thus, for chest X-ray procedures performed 

prior to 1963, DCF values from Table 4.0-1 of ORAUT-OTIB-0006 (ORAU 2003) were used to 

estimate organ doses. [Where DCF values were not provided in Table 4.0-1 (i.e., for HVLs equivalent 

to 1.5 and 2.5 mm of Al), guidance was provided by the ORAU COC Medical X-ray Lead to estimate 

and verify the values used in Table 3-5 of this report.] These tables provide average absorbed organ 

doses for specific selected medical radiography procedures related to an entrance air kerma without 

backscatter of 1 Gy for various beam qualities expressed in terms of HVL of aluminum. However, the 

tables do not include all organs identified in the Interactive RadioEpidemiological Program (IREP) 

code. For organs included in IREP that are not specifically identified in ICRP 34, the DCFs selected 

were those for organs identified in ICRP 34 that were anatomically the closest, as specified in (ORAU 

2003). Thus, the factor for lung should be used for other organs in the thoracic cavity (i.e., the 

thymus, esophagus, stomach, and liver/gall bladder). Because an appreciable fraction of the 

skeleton, in particular the trabecular bone, which has a large surface-to-volume ratio, is in the trunk, 

the DCF for lung should also be used to compute dose to the bone surfaces. For organs in the 

abdomen (i.e., urinary bladder, colon, and uterus) the DCF for the ovaries should be used. These 

surrogate organs are summarized in Table 3-7. 

Because, as discussed above, 1 R was taken to be 10 mGy (1 cGy) of kerma, conversion could easily

be made if the beam quality was known. Measured beam quality data were not consistently found for 

the ORNL site and, therefore, data that were located were not used. The applied voltage and filtration 

were provided in the site description (and modified as noted in Table 3-3), and an estimate of beam 

quality could be made from these data. Because absorbed organ dose increases as a function of 

HVL for a given amount of filtration and exposure (mAs), for conservatism the upper limit on the likely 

beam quality was calculated and rounded up (claimant favorable assumption) to match the closest 

value in the tables in ICRP 34 or ORAU (2003). 

The assumed operating parameters used to calculate ESE and organ dose are listed in column 2 of 

Table 3-3. Several items were either not obtained or not clear and assumptions were necessary to be 

able to calculate organ doses. The examination type, frequency, ESEs, and HVLs used to calculate 

organ doses are listed in Table 3-4. The DCFs from ICRP 34 (1982) and ORAU (2003) used to 

calculate organ doses are listed in Table 3-5. The calculated organ doses are listed in Table 3-6. 

ICRP 34 does not give DCFs for several organs that are inputs to IREP, so other organs were used 

as surrogates based on their positions in the body. The surrogates and associated organs are listed 

in Table 3-7. In addition, since there are no DCFs for female breasts given for the AP and Lateral 

lumbar spine examinations, the DCFs for the similar Upper GI projections were used to estimate 

organ dose. Table A6 in ICRP 34 states that for lumbar spine exams, DCFs were "Not computed but 

small compared with projections listed above." The use of the Upper GI DCFs should therefore be 

claimant favorable. 

3.4 UNCERTAINTY ANALYSIS FOR ORNL RADIOGRAPHY DOSES

Error (deviation from the correct, true, or conventionally accepted value of a quantity) and uncertainty

(defined in terms of the potential range of a stated, measured, assumed, or otherwise determined 

value of a quantity) provide an indication of the confidence of the dose estimates. Error implies 

knowledge of what the correct or actual value is, which is, of course, not known. Therefore, the more 

appropriate factor is uncertainty, which is expressed in terms of a confidence level (e.g., 99% -- that 

the correct or true value, although not actually known, has a 99% probability of falling within the range 

cited) and includes both precision or reproducibility of the measurement and accuracy, or how close 

the measurement or estimate of dose comes to the actual or correct value.
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 15 of 27

In theory a large number of factors can introduce uncertainties or affect the X-ray machine output 

intensity and dose to the worker. Occupational medical X-ray exposures (e.g., ESEs) at ORNL were 

derived from equipment operating factors. Several factors can have an impact on dose uncertainty: 

1. Variation in applied voltage

2. Variation in tube current

3. Variation in exposure time

4. Distance from the worker to the source of the X-rays (SSD)

The influence of such other factors as use of screens, grids, reciprocity failure, film speed, and 

development, while potentially variable, would not affect the beam output intensity.

Theoretically, for a given set of machine settings and parameters, X-ray output should be constant 

and unvarying. However, this is not true in practice, although output is essentially constant unless 

focal spot loading occurs, as might be the case if the power rating of the machine is exceeded. It is 

unlikely that power ratings were ever exceeded because such an event would be difficult to achieve in 

practice and could result in damage to the X-ray tube. However, even with the use of constant 

voltage transformers to control line voltages, slight variations might occur in line voltage input or other 

internal voltages, which in turn could alter the applied voltage of the output beam. In general, for a 

given applied voltage setting, variation in kVp falls within ±5% of the machine setting (Seibert, Barnes, 

and Gould 1991). As noted above, beam intensity is approximately proportional to the 1.7 power of 

the applied voltage; this translates to an uncertainty of approximately ±8.6% with respect to output 

beam intensity in the 80 to 100 kVp. For conservatism, this is rounded up to ±9%.

Similarly slight variations in tube current are normal. As a tube ages, or heats from use, current can 

change and typically will drop. With all other factors constant, beam intensity will be reduced in direct 

proportion to the change in tube current. Typically, the reduction in beam output from current 

variation is not more than a few percent under normal operating conditions. Large decreases are 

readily detectable and result in maintenance on the machine to restore the output or, as a temporary 

measure, an increase in the current or kVp to provide the necessary intensity for proper radiography. 

There is no evidence to suggest that such temporary measures were ever necessary or applied at 

ORNL. For a given kVp setting, the output of the beam is a function of the tube current, which in turn 

is measured by a milliammeter, which measures average tube current. The measurement is subject 

to uncertainties. There might be minor changes in output as the tube heats from normal use. 

Because these variations are typically small, the estimated uncertainty in beam output attributable to 

current variation is ±5%. 

Another parameter that has potential to affect the dose from a diagnostic radiograph, perhaps 

significantly, relates to the time of exposure. A full-wave-rectified machine produces 120 pulses per 

second of X-rays. In an exposure time of 1/20 of a second, six pulses would result. A small error in 

the timer that resulted in a change of only ±1 pulse would affect the output by ±17%. For an exposure 

time of 1/30 of a second, the change in output corresponding to a deviation of ±1 pulse is ±25%. 

Early mechanical timers were notoriously inaccurate. Accuracy improved significantly with the 

introduction of electronic timers. [ORNL site surveys indicated that the unit used onsite during the late 

1970s and mid 1980s (the Westinghouse Riviera) caused exposures approximately 20 to 25% greater 

than what was expected. A factor of 1.25 was added to the estimated ESEs to account for this and 

the ESE and organ doses values for the time period of 1964-1990 in Tables 3-4 and 3-6 respectively 

were corrected for this.] For conservatism, the assumed uncertainty in beam output attributable to 

timers has an upper limit of ±25%. 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 16 of 27

The final factor likely to affect worker dose relates to the distance of the worker from the source of the 

X-rays, which is a determinant of the ESE. For a given individual, the SSD will be determined largely 

by the body thickness of the worker and the accuracy of the positioning. For a typical worker, the 

estimated variation in SSD is no more than a few centimeters, with an upper limit of perhaps 7.5 cm. 

Using the inverse square of the distance, this indicates an uncertainty of ±10% from this source.

There are two approaches to determine the combined uncertainty from the five potential sources of 

dose uncertainty listed above. The first, and most conservative, because it gives the greatest range, 

would be to assume that the uncertainties are additive, which would give an uncertainty range of 9 + 5 

+ 25 + 10 = + 49%. However, a more reasonable approach would be to assume that the uncertainties 

are in fact random, and to compute the statistical root mean square (RMS) value. The RMS value is 

simply the square root of the sum of the squares, and computes as ±28.8%. Rounding this up to 

±30% would seem to provide an adequate and suitably conservative indication of uncertainty. Thus, 

for an individual ESE or derived organ dose, an uncertainty of ±30% (1 σ) can be assumed. For 

further conservatism it might be appropriate to assume that errors are all positive, and only +30% 

should be used. 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 17 of 27

Table 3-2. X-ray operating parameters, dates of use, and frequency of examinations (provided by ORNL). Dates X-ray equipment Location Techniques X-ray conditions People involved Age dependence

Prior to October 

3, 1947

Not accurately known, but 

possibly a Westinghouse 

Fluorodex 60-120 kVp

Oak 

Ridge 

Hospital

Stereo PFG (2 

views), PA chest Xray

(possibly others)

Not accurately known Employees and 

preplacement

October 3, 1947 

to end of 1963

Picker 200-mA Control & 

Generator- Model R-2

ORNL Chest X-ray, one 

film, PA projection

Filter=0.04 mm Al

76 kVp, 200 mA @ 1/20 sec., 

183 cm. distance, w/ 20-cm 

cone

Employees and 

Preplacement

April 6, 1950, to 

September 23, 

1953

Picker 200-mA Control & 

Generator- Model R-2

ORNL Lumbar spine series, 

4 films: AP, AP 

spot, Lateral, and 

Lateral spot

AP & AP spot

Filter=0.04 mm Al, 80 kVp, 40 

mA, 4 sec @ 99 cm. distance, 

w/ 20-cm cone

Craft workers

Lat & Lat spot

Filter=0.04 mm Al, 86 kVp, 40 

mA, 8 sec @ 99 cm distance, w/ 

20-cm cone

End of 1963 to 

November 1990

Westinghouse Riviera 300 

mA, 125 kVp

ORNL Chest X-ray, one 

film, PA projection

Filter 1.5 mm Al, 107 kVp, 300 

mA, 0.01 sec, @ 183 cm 

distance

Preplacement

1976 to 

November 1990

Westinghouse Riviera 300 

mA, 125 kVp

ORNL Chest X-ray, one 

film, PA projection

Filter 1.5 mm Al, 107 kVp, 300 

mA, 0.01 sec, @ 183 cm 

distance

Preplacement;

employees in 

respirator/asbestos 

programs (every 3 

years)

November 1990 

to April 18, 1996

Bennett High Frequency 

Quartz 600 Series

ORNL Chest X-ray, one 

film, PA projection

Filter 2.0 mm Al, 110 kVp, 300 

mA, 3.2 mAs, @ 183 cm 

distance

Preplacement; 

respirator/asbestos 

program employees

< 40 years old, every 

3 years; 40-49 years 

old, every 2 years; > 

49 years old, every 

year

April 18, 1996 Bennett High Frequency 

Quartz 600 Series

ORNL Chest X-ray, two 

films, PA and lateral 

projections

PA

Filter 2.0 mm Al, 110 kVp, 300 

mA, 3.2 mAs, @ 183 cm 

distance

Preplacement; 

respirator/asbestos 

program employees

< 40 years old, every 

3 years; 40-49 years 

old, every 2 years; 

>49 years old, every 

Lateral year

Filter 2.0 mm Al, 125 kVp, 300 

mA, 8.0 mAs, @ 183 cm 

distance

2002 Bennett High Frequency 

Quartz 600 Series

ORNL Chest X-ray, two 

films, PA and lateral 

projections

PA

Filter 2.0 mm Al, 110 kVp, 300 

mA, 3.2 mAs, @ 183 cm 

distance

Asbestos program 

employees

annually for workers 

45 and over 

Lateral

Filter 2.0 mm Al, 125 kVp, 300 

mA, 8.0 mAs, @ 183 cm 

distance
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 18 of 27

Table 3-3. Assumptions made to operating parameters provided by ORNL and where default 

parameters were used. 

ORNL-provided operating parameter Assumed operating parameter

PFGs were taken at Oak Ridge Hospital for a period prior 

to 1947.

All employees were assumed to have received preplacement 

stereo PFG for employment purposes between 1943 and 

October 3, 1947.

Skin exposure for the Oak Ridge Hospital was given in a 

survey conducted by ORNL Medical Staff of PFG unit of 

1.4 R.

ESE from stereo PFG = 2.8 rem (assume 2 exposure views) 

from the Oak Ridge Hospital survey forms.

14” × 17” radiographs of chest were noted for most site 

personnel for all retakes, routine annual, and termination 

examinations unless waived.

All retakes, routine annual, and termination examinations had 

PA chest X-ray examination unless medical records indicate 

differently.

ESE from early 14” × 17” radiographs conducted at Oak 

Ridge Hospital not known.

ESE for 14” × 17” radiographs not performed at ORNL = 0.2 

rem (default)

Inherent filtration on Picker R-2 Unit = 0.04 mm Al. Review of Lincoln and Gupton documents (1958a and 

1958b) indicates that a filtration value of 1 mm Al was used 

with the Picker R-2 unit.

Total filtration for Picker R-2 unit not given. HVL = 1.5 mm Al for organ dose calculations. 

Operating parameters for Picker were 76 kVp/10 mAs 

(PA chest), 80 kVp/160 mAs (AP lumbar spine), and 86 

kVp/320 (Lat lumbar spine).

Operating parameters for Picker are 76 kVp/10 mAs (PA 

chest), 80 kVp/160 mAs (AP lumbar spine), and 86 kVp/320 

(Lat lumbar spine).

SIDs for all chest, PFG chest, and lumbar spine 

examinations were 72, 48, and 39 in., respectively.

SIDs for all chest, PFG chest, and lumbar spine 

examinations were 183, 122, and 99 cm, respectively.

Lumbar spine exams conducted on craft individuals from 

4/6/50 to 9/23/53.

Lumbar spine exams conducted on craft individuals from 

4/6/50 to 9/23/53.

PA and Lat chest thicknesses and distance from body to 

imaging surface not given.

Assume PA and Lat chest thicknesses of 26 and 34 cm, 

respectively; AP and Lat LS thicknesses of 26 and 34 cm, 

respectively; and distance from body to imaging surface of 5 

cm.

Exposure time for Westinghouse Riviera was given as 

0.01 sec.

Review of equipment in use indicates that 3 mAs probably 

would have been low for that period and, therefore, exposure 

time was increased to 0.1 sec giving 30 mAs. In addition, 2 

assessments conducted on the Westinghouse unit indicated 

a variation in the timer of between 20% and 25%. The ESE 

value for the 1964 - 1990 period in Table 3-4 was therefore 

increased by a factor of 1.25. 

Operating parameters for Westinghouse Riviera were 107 

kVp/3 mAs (PA chest).

Operating parameters for Westinghouse Riviera were 107 

kVp/30 mAs (PA chest).

Operating parameters for Bennett are 110 kVp/3.2 mAs 

(PA chest) and 125 kVp/8 mAs (Lat chest).

Operating parameters for Bennett are 110 kVp/3.2 mAs (PA 

chest) and 125 kVp/8 mAs (Lat chest).

Filtration values were given of 3.0, 0.04, 1.5, and 2.0 mm 

Al, respectively for Oak Ridge Hospital, Picker, 

Westinghouse, and Bennett units. HVL values were not 

given by ORNL.

Assume that HVL values for Oak Ridge Hospital, Picker, 

Westinghouse, and Bennett units are 2.5, 1.5 (2.0 for Lumbar 

Spine exams), 3.0, and 3.5 mm Al, respectively.

Though cone shield in place, measurements of organ 

doses indicate that the collimation of X-ray beam was bad 

for the Oak Ridge Hospital and Picker units.

Use uncollimated DCFs for organ dose estimates for the Oak 

Ridge Hospital and Picker units. Collimation of the beam for 

the Westinghouse and Bennett units is assumed to be good 

and ICRP 34 values used.

Waveform information not given for any unit. Picker R-2 and Westinghouse Riviera were single-phase 

units; Bennett unit was high-frequency.

Preplacement examinations indicated. Preplacement, retakes, routine annual, and termination X-ray 

examinations given.

Respirator and asbestos workers had different X-ray 

examination frequencies from approximately 1976 to 

present.

Assumed frequencies for respirator and asbestos workers 

listed in Table 3-2.
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 19 of 27

Table 3-4. Values used to calculate organ dose.

Years included Examination Workers affected ESE (rem) HVL (mm Al)

Before 1947 Stereo PFG a Preplacement 2.8E+00 2.5

Before 1947 Chest PA PFG retake, annual, and termination 2.0E-01 2.5

1947-1963 Chest PA Preplacement, annual, and termination 5.6E-02 b 1.5

1950-1953 LS AP c Preplacement for craft workers 4.0E+00 2.0

1950-1953 LS Lat d Preplacement for craft workers 1.0E+01 2.0

1964-1990 Chest PA e Preplacement, others as needed f 1.6E-01 3.0

1990-2002 Chest PA Preplacement, others as needed f 2.2E-02 3.5

1996-2002 Chest Lat Preplacement, others as needed f 6.2E-02 3.5

a. The ESE for the Stereo PFG represents both exposures. Values in Table 3-6 also indicate organ doses from both 

exposures.

b. Though Lincoln and Gupton (1958a) indicates a measured ESE of 2.1E-02 rem, this value is low compared to expected 

exposures between 1947 and 1963. The ESE provided in this Table was estimated using the equipment’s operating 

parameters. This value is approximately a factor of 2.7 greater than that measured and is claimant favorable. 

c. The ESE for the LS AP represents both the AP and spot AP exposures (i.e., 2 exposures). Values in Table 3-6 also 

indicate organ doses from both exposures.

d. The ESE for the LS Lat represents both the Lat and spot Lat exposures (i.e., 2 exposures). Values in Table 3-6 also 

indicate organ doses from both exposures.

e. Two ORNL surveys indicated that the timer may have caused up to a 25% increase in exposure. The estimated ESE 

value was therefore increased by the factor of 1.25. 

f. Asbestos workers and others involved in respiratory protection programs examined periodically (see Table 3-2).
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 20 of 27

Table 3-5. Average absorbed dose per unit entrance air kerma for selected X-ray views, organs, and beam qualities.

a

Organ View b

Source-image 

distance (cm)

Image 

receptor size 

(cm)

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 1.5 mm Al

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 2.0 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 2.5 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 3.0 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 3.5 mm Al

Thyroid

Chest PA 183 35.6 × 43.2 120 (c) 21 174 46 62

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 151

Stereo PFG 122 10.2 × 25.4 -- -- 174 -- --

LS AP 99 35.6 × 43.2 -- 0.2 -- -- --

LS Lat. 99 35.6 × 43.2 -- 0.01 -- -- --

Eye/Brain

Chest PA 183 35.6 × 43.2 11 21 32 46 62

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 151

Stereo PFG 122 10.2 × 25.4 -- -- 32 -- --

LS AP 99 35.6 × 43.2 -- 0.2 -- -- --

LS Lat. 99 35.6 × 43.2 -- 0.01 -- -- --

Ovaries

Chest PA 183 35.6 × 43.2 N/A 0.6 N/A 1.8 3.2

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 1.6

Stereo PFG 122 10.2 × 25.4 -- -- N/A -- --

LS AP 99 35.6 × 43.2 -- N/A -- -- --

LS Lat. 99 35.6 × 43.2 -- N/A -- -- --

Testes

Chest PA 183 35.6 × 43.2 N/A 0.01 N/A 0.01 0.01

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 0.1

Stereo PFG 122 10.2 × 25.4 -- -- N/A -- --

LS AP 99 35.6 × 43.2 -- N/A -- -- --

LS Lat. 99 35.6 × 43.2 -- N/A -- -- --

Lungs (male)

Chest PA 183 35.6 × 43.2 243 335 419 496 565

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 276

Stereo PFG 122 10.2 × 25.4 -- -- 419 -- --

LS AP 99 35.6 × 43.2 -- 62 -- -- --

LS Lat. 99 35.6 × 43.2 -- 10 -- -- --

Lungs (female)

Chest PA 183 35.6 × 43.2 250 355 451 535 610

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 310

Stereo PFG 122 10.2 × 25.4 -- -- 451 -- --

LS AP 99 35.6 × 43.2 -- 62 -- -- --

LS Lat. 99 35.6 × 43.2 -- 10 -- -- --

Breast

Chest PA 183 35.6 × 43.2 18 32 49 69 91

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 316

Stereo PFG 122 10.2 × 25.4 -- -- 49 -- --

LS AP 99 35.6 × 43.2 -- 18 (d) -- -- --

LS Lat. 99 35.6 × 43.2 -- 9.5 (d) -- -- --

Uterus (embryo)

Chest PA 183 35.6 × 43.2 N/A 0.7 N/A 2.3 3

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 1.4

Stereo PFG 122 10.2 × 25.4 -- -- N/A -- --

LS AP 99 35.6 × 43.2 -- N/A -- -- --

LS Lat. 99 35.6 × 43.2 -- N/A -- -- --
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 21 of 27

Table 3-5 continued

Organ View b

Source-image 

distance (cm)

Image 

receptor size 

(cm)

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 1.5 mm Al

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 2.0 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 2.5 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 3.0 mm Al 

Dose conversion 

factor (mGy per 

Gy air kerma) for 

HVL = 3.5 mm Al

Bone marrow (male)

Chest PA 183 35.6 × 43.2 49 69 92 117 146

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 61

Stereo PFG 122 10.2 × 25.4 -- -- 92 -- --

LS AP 99 35.6 × 43.2 -- 24 -- -- --

LS Lat. 99 35.6 × 43.2 -- 15 -- -- --

Bone marrow (female)

Chest PA 183 35.6 × 43.2 43 63 86 112 141

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 48

Stereo PFG 122 10.2 × 25.4 -- 24 86 -- --

LS AP 99 35.6 × 43.2 -- 15 -- -- --

LS Lat. 99 35.6 × 43.2 -- -- -- -- --

Total body (male)

Chest PA 183 35.6 × 43.2 83 108 131 153 174

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 94

Stereo PFG 122 10.2 × 25.4 -- -- 131 -- --

LS AP 99 35.6 × 43.2 -- 83 -- -- --

LS Lat. 99 35.6 × 43.2 -- 38 -- -- --

Total body (female)

Chest PA 183 35.6 × 43.2 66 93 118 140 161

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 89

Stereo PFG 122 10.2 × 25.4 -- -- 118 -- --

LS AP 99 35.6 × 43.2 -- 83 -- -- --

LS Lat. 99 35.6 × 43.2 -- 38 -- -- --

Skin (e)

Chest PA 183 35.6 × 43.2 1.28 1.32 1.36 1.39 1.41

Chest Lat. 183 35.6 × 43.2 -- -- -- -- 1.41

Stereo PFG 122 10.2 × 25.4 -- -- 1.36 -- --

LS AP 99 35.6 × 43.2 -- 1.32 -- -- --

LS Lat. 99 35.6 × 43.2 -- 1.32 -- -- --

a. Dose conversion factors (DCFs) for HVLs of 1.5, 2.0, 3.0, and 3.5 mm Al are from Tables A.2 through A.9 of ICRP 34, assuming good collimation of the beam, unless otherwise noted. The DCFs for the 

2.5 mm HVL were obtained from Table 4.0-1 of ORAUT-OTIB-0006 because data indicate that the collimation may have been questionable. “N/A” means dose values represent measurements or default 

values rather than product of ESE and DCF. 

b. LS = lumbar spine.

c. Value per OTIB-0006, rev. 2 (ORAU 2003) due to questionable collimation of the beam. 

d. Dose conversion factors for lumbar spine examination not given in ICRP 34. Values for the respective Upper G.I. exams (i.e., AP and Lat) were used instead. 

e. Values are dimensionless backscatter factors from Table B.8 of NCRP 102 (1989). Values for HVLs = 2.5 and 3.5 were obtained via linear interpolation. 
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 22 of 27

Table 3-6. Organ dose estimates for ORNL chest and lumbar spine radiographs to be used as IREP inputs.

a

Organ View

Organ dose (rem) 

prior to 1947

Organ dose (rem) 

1947–1963

Organ dose (rem) 

1950–1953

Organ dose (rem) 

1964–1990

Organ dose (rem) 

1990–present

Organ dose (rem) 

1996–present

Thyroid Chest PA 3.48E-02 6.72E-03 -- 7.36E-03 1.36E-03 --

Chest Lat. -- -- -- -- -- 9.36E-03

Stereo PFG 4.87E-01 (c) -- -- -- -- --

LS AP -- -- 8.00E-04 (c) -- -- --

LS Lat. -- -- 1.00E-04 (c) -- -- --

Eye/Brain Chest PA 6.40E-03 6.16E-04 -- 7.36E-03 1.36E-03 --

Chest Lat. -- -- -- -- -- 9.36E-03

Stereo PFG 8.96E-02 (c) -- -- -- -- --

LS AP -- -- 8.00E-04 (c) -- -- --

LS Lat. -- -- 1.00E-04 (c) -- -- --

Ovaries Chest PA 2.5E-02 (b) 5E-03 (e) -- 2.88E-04 7.04E-05 --

Chest Lat. -- -- -- -- -- 9.92E-05

Stereo PFG 5.0E-02 (b) (c) -- -- -- -- --

LS AP -- -- 1.12E+00 (c) (e) -- -- --

LS Lat. -- -- 1.52E+00 (c) (e) -- -- --

Testes Chest PA 5.0E-03 (b) 2E-03 (e) -- 1.60E-06 2.20E-07 --

Chest Lat. -- -- -- -- -- 6.20E-06

Stereo PFG 1.0E-02 (b) (c) -- -- -- -- --

LS AP -- -- 5.40E-02 (c) (e) -- -- --

LS Lat. -- -- 1.12E-01 (c) (e) -- -- --

Lungs (male) Chest PA 8.38E-02 1.36E-02 -- 7.94E-02 1.24E-02 --

Chest Lat. -- -- -- -- -- 1.71E-02

Stereo PFG 1.17E+00 (c) -- -- -- -- --

LS AP -- -- 2.48E-01 (c) -- -- --

LS Lat. -- -- 1.00E-01 (c) -- -- --

Lungs (female) Chest PA 9.02E-02 1.40E-02 -- 8.56E-02 1.34E-02 --

Chest Lat. -- -- -- -- -- 1.92E-02

Stereo PFG 1.26E+00 (c) -- -- -- -- --

LS AP -- -- 2.48E-01 (c) -- -- --

LS Lat. -- -- 1.00E-01 (c) -- -- --

Breast Chest PA 9.80E-03 1.01E-03 -- 1.10E-02 2.00E-03 --

Chest Lat. -- -- -- -- -- 1.96E-02

Stereo PFG 1.37E-01 (c) -- -- -- -- --

LS AP -- -- 7.20E-02 (c) -- -- --

LS Lat. -- -- 9.50E-02 (c) -- -- --

Uterus (embryo) Chest PA 2.5E-02 (b) 5E-03 (e) -- 3.68E-04 6.60E-05 --

Chest Lat. -- -- -- -- -- 8.68E-05

Stereo PFG 5.0E-02 (b) (c) -- -- -- -- --

LS AP -- -- 1.12E+00 (c) (e) -- -- --

LS Lat. -- -- 1.52E+00 (c) (e) -- -- --

Bone marrow (male) Chest PA 1.84E-02 2.74E-03 -- 1.87E-02 3.21E-03 --

Chest Lat. -- -- -- -- -- 3.78E-03

Stereo PFG 2.58E-01 (c) -- -- -- -- --

LS AP -- -- 9.60E-02 (c) -- -- --

LS Lat. -- -- 1.50E-01 (c) -- -- --
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 23 of 27

Table 3-6 continued

Organ View

Organ dose (rem) 

prior to 1947

Organ dose (rem) 

1947–1963

Organ dose (rem) 

1950–1953

Organ dose (rem) 

1964–1990

Organ dose (rem) 

1990–present

Organ dose (rem) 

1996–present

Bone marrow (female) Chest PA 1.72E-02 2.41E-03 -- 1.79E-02 3.10E-03

Chest Lat. -- -- -- -- -- 2.98E-03

Stereo PFG 2.41E-01 (c) -- -- -- -- --

LS AP -- -- 9.60E-02 (c) -- -- --

LS Lat. -- -- 1.50E-01 (c) -- -- --

Total body (male) Chest PA 2.62E-02 4.65E-03 -- 2.45E-02 3.83E-03 --

Chest Lat. -- -- -- -- -- 5.83E-03

Stereo PFG 3.67E-01 (c) -- -- -- -- --

LS AP -- -- 3.32E-01 (c) -- -- --

LS Lat. -- -- 3.80E-01 (c) -- -- --

Total body (female) Chest PA 2.36E-02 3.70E-03 -- 2.24E-02 3.54E-03 --

Chest Lat. -- -- -- -- -- 5.52E-03

Stereo PFG 3.30E-01 (c) -- -- -- -- --

LS AP -- -- 3.32E-01 (c) -- -- --

LS Lat. -- -- 3.80E-01 (c) -- -- --

Skin (d) Chest PA 2.72E-01 7.17E-02 -- 2.22E-01 3.10E-02 --

Chest Lat. -- -- -- -- -- 8.74E-02

Stereo PFG 3.81E+00 (c) -- -- -- -- --

LS AP -- -- 5.28E+00 (c) -- -- --

LS Lat. -- -- 1.32E+01 (c) -- -- --

a. The exposures for various date ranges should be matched to the X-ray examinations listed in Table 3-2. 

b. Default value from OTIB-0002, rev. 2 (ORAU 2003).

c. Value is doubled to account for two exposures.

d. Skin dose values include backscatter factors from Table B.8 of NCRP 102 (1989).

e. Organ dose values for the testes, ovaries, and uterus for lumbar spine for 1950 – 1953 reflect actual measurement reported in (Lincoln and Gupton 1958b).
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 24 of 27

Table 3-7. Surrogate and associated organs.

Surrogate Associated organs

Lung Thymus, esophagus, stomach, liver, gall bladder, 

spleen, remainder, and bone surface

Ovaries Urinary/bladder, uterus, and colon & rectum
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 25 of 27

REFERENCES

BRH (Bureau of Radiological Health), 1970, Radiological Health Handbook, Revised Edition, U.S. 

Department of Health, Education and Welfare, Rockville, Maryland, p. 159.

Cahoon, J. B, 1961, Formulating X-Ray Technics, Duke University Press, Durham, North Carolina, p. 

183.

Fuchs, Arthur W, 1958, Principles of Radiographic Exposure and Processing, Charles W, Thomas,

Springfield, p. 184.

Halliburton, R. E., 1985, “X-10 Medical X-ray Compliance Survey results,” September 10, 1985.

Handloser, J. S., 1951, “Radiation Doses from Diagnostic X-ray Studies,” Radiology 57:252-254.

ICRP (International Commission on Radiological Protection), 1982, “Protection of the Patient in 

Diagnostic Radiology,” Annals of the ICRP, ICRP Publication 34, 9(2/3):1-82. 

ICRU (Fifth International Congress on Radiology), 1937, “Recommendations of the International 

Committee for Radiological Units.” Radiology 29:634.

ICRU (International Commission on Radiation Units and Measurements), 1998, Fundamental 

Quantities and Units for Ionizing Radiation, ICRU Report 60, Bethesda, Maryland.

Kathren, R. L., 1965, "Spectral and Output Measurements of a Wide Beam K-Fluorescence Radiator," 

in Hazards Control Quarterly Report No. 20, U.S. Atomic Energy Commission Report 

UCRL-14151, pp. 1-5.

Kathren, R. L. and G. R. Petersen, 1989, “Units and Terminology of Radiation Measurement: A 

Primer for the Epidemiologist,” Amer. J. Epidemiol. 130:1076-1087.

Lincoln, T. A. and E. D. Gupton, 1958a, “Radiation Dose to Gonads from Diagnostic X-Ray 

Exposure,” The Journal of the American Medical Association, vol. 166, pp. 233-239, January 

18, 1958.

Lincoln, T. A. and E. D. Gupton, 1958b, “Radiation Doses in Diagnostic X-Ray Procedures,” 

Radiology, vol. 71, pp. 208-215, August 1958.

Magie, W. F., 1896, American Journal of Medical Science, 111:251-255.

NBS (National Bureau of Standards), 1936, X-ray Protection, National Bureau of Standards Handbook 

20, U.S. Government Printing Office, Washington D.C.

NBS (National Bureau of Standards), 1949, Medical X-ray Protection Up To Two Million Volts, 

National Bureau of Standards Handbook 41, U.S. Government Printing Office, Washington, 

D.C. 

NBS (National Bureau of Standards), 1955, X-ray Protection, National Bureau of Standards Handbook 

60, U.S. Government Printing Office, Washington, D.C. 

NCRP (National Council on Radiation Protection and Measurements), 1968, Medical X-Ray and 

Gamma-Ray Protection for Energies Up To 10 MeV, NCRP Report No. 33, Washington, D.C. 
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NCRP (National Council on Radiation Protection and Measurements), 1985, SI Units in Radiation 

Protection and Measurements. NCRP Report No. 82, Bethesda, Maryland.

NCRP (National Council on Radiation Protection and Measurements), 1989, Medical X-Ray, Electron 

Beam and Gamma-Ray Protection up to 50 MeV (Equipment Design, Performance and Use), 

NCRP Report No. 102, Bethesda, Maryland.

NIOSH (National Institute for Occupational Safety and Health), 2002, External Dose Reconstruction 

Implementation Guideline, Rev. 1, OCAS-IG-001, Office of Compensation Analysis and 

Support, Cincinnati, Ohio.

Ohnesorge, W. F., “Exposures Received from Typical Diagnostic X-Ray Examinations at ORNL and 

Safety Review of the Medical X-Ray Facility,” March 12, 1979.

ORAU (Oak Ridge Associated Universities), 2003, Technical Information Bulletin: Dose 

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Ohio, p. 67.

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963.

Tuck, T. L., 2003, personal conversation, September 2003.
Effective Date: 04/20/2004 Revision No. 00 Document No. ORAUT-TKBS-0012-3 Page 27 of 27

GLOSSARY

beam quality

The beam quality is used to describe the “hardness” of the X-ray beam. The beam quality is 

increased by inserting filtration (typically Aluminum shielding) between the X-ray source and 

target. The addition of filtration is used to shield much of the useless, low energy photons and 

typically increases the resulting film.

collimation

Was used to focus and minimize the secondary and scattered photons that may irradiate other 

organs that are not important for diagnosis. A 20-cm cone was used early at ORNL to reduce 

this scatter. 

photofluorography (PFG)

A chest X-ray examination given at the Oak Ridge Hospital prior to X-ray equipment being 

acquired and used at ORNL. The PFG films seen at ORNL were 4” × 10” films showing two 

chest films that could be reviewed by a radiologist to see 3-D views of an individual’s chest. 

The films were not X-ray films but were captured by taking two pictures with a camera of an 

image intensifying screen.

termination examination

A medical examination provided upon an employee’s release from ORNL.